Production of translucent textile material



Aug. 16,1949. MELLOR ETAL 2,478,974

PRODUCTION OF TRANSLUCENT TEXTILE MATERIAL Filed 001;. 9, 1945 .INVENTORS A-MELLOR.

R. J. MANN. BY D. FmuAYsoN,

Patented Aug. 16, 1949 PRODUCTION OFTRANSLUCENT TEXTILE.

MATERIAL Albert Mellor, Ralph James. Mann, Donald Finl'ayson, and Albert William Morledgeefladfield, Spondon, near Derby, England; assignors to- Cela-nese Corporation of America, a corporation of Delaware Application octoberj 9, 1945, Serial: No. 621,378: in Great Britain October so, 1944 8. GlaimS. (Cl; 31 1-7-56) This invention relates to the treatment of textile materials and especially to'the. dressing of textile materials with resins, drying oils, rubber, cellulose esters or ethers, and similar substances.

Textile materials, especially textile fabrics, coated or impregnated with a variety of sub stances, for example synthetic and natural resins, drying oils, rubber, natural or synthetic rubberlike materials, and cellulose esters or ethers, '(including compositions having a basis of one or more of the foregoing), are manufactured. extensively and: have a wide field of use. Thedrying oil or other substance can be present in various proportions in relation to the Weight of the textile material and: mayor may not 'bein sulficient proportion to close completely the poresof the textile. Such a material is the oiled sills, made by impregnating a silk fabric with boiled linseed oil and allowing the latter to dry in the air by oxidation. This and: similar materials made by impregnatin other textile fabrics with boiled linseed oil or with solutions of resins or other of the above mentioned productsin organic liquids, often hydrophobe, are: used: Water-resistant coverings, for electrical insulation, and for many other purposes.

When preparing such coated or impregnated textile materials it is often found that the: treated material does not appear uniform; Thus when thin textile fabrics are impregnated withboiled linseed oil and the latter allowed to dry the appearance of the fabric may be marred by'the presence of opaque yarns which usually appear white by reflected light. The presence of such yarns is very undesirablewhere a uniform degree of transparency is a 'desiderat-um. The efiectcan usually :be observed when the untreated textile is immersed in the oil or in a solution of a resin or other substance in a hydrophobe liquid or even in ahydrophobe liquid. free-from filmefor-ming substances.

Wehave found that from the point of view of avoiding the foregoing troubles it is very advantageous to subject textile fibres, particularly cellulose fibres, to the combined action of water and a hydrophobe organic compound in fluid form, for example to subject the fibres to. the action of a hydrophobe organic. liquid; while the fibres are wet with water and especially while they carry a limited proportion of water. Thus, in the case of a fabric of regenerated cellulose yarns (made by stretching cellulose acetate yarns in wet steam and subsequently saponi-fyi ng) which on immersicninb'enzehe, even long immersion, exhibits the above mentioned opaque yarns,

if it is first moistened with water so as to be damp to the touchand then immersed in benzene some of the yarns appear opaque at first but rapidly become, transparent and the whole fabric becomes blarified and'substantially uniformly translucent in. the benzene. if the fabric, is then oiled with boiled linseed oila product of uniform appearance is obtained even when the benzene is evaporatedoff'from the material before the oiling. Further, it is not essential to subject the moistened fabric to theaction of benzene; good results as regardsthe appearance of the oiled material can be obtained by introducing'the moist fabric directly into the oil. These results are very remarkable since it would. be expected that the moistening: of the fabricwould be prejudicial to the subsequent action of the benzene and/or 011.

Various hydrophobe organic compounds can be employed to produce the desired effect. Conveni'entl'y' liquids of suchvolatility that they can readily be removed from the textile by evaporation used", more particularly when the textile is subsequently to be impregnated or coated with a film-forming material. They can be for instance aliphatic or aromatichydrocarbons, for example benezene asmentioned above, toluene, xylene; sol-vent naphtha, or light fractions of petroleum. Also halogenated hydrocarbons can be used for exam-pie carbon tetrachloride or perchlorethylene. Further, difiicultly volatile or-substantially non-volatile hydrophobe organic compounds can; be used, for example dimet'hyl phthalate, diethyl phth'alate, di-( methoxyethylo phthalate, and methylc'yclohexanol all of which are liquids of low volatility, the esters-jot phthalic acid being substantially non-volatile. They can be used aloneor as mixtures with volatile hydr'o phobeliquids or volatile water-miscible liquids, e. g. acetone; It has also been found" that the desired clarification can be obtained by the action of vapours or hydrophobe organic compoundsthough as a rule the action of the latter is much 7 slower than, that or the liquid. For example. the

moist fabric can be exposed. for. several hours to air saturatedwith the vapour of benzene or solvent naphtha,

The hydrophobe liquids can also be liquids which: are: capable of yielding a film on. drying, for example drying oils, e; "g. tu-ng oil or the linseed oil mentioned above, or solutions of filmforming. substances in hydrophobreliquids: the solutions being capable of yielding coatings by evaporation of the nydrophobe liquid.

The proportion of water desirable on the textile material for the desired clarifying effect to be obtained on subjecting the material to the action of the hydrophobe liquid is usually substantially greater than the normal moisture content of the material. Preferably is should be at least equal to that held by the material when in been immersed in water and then pressed between sheets of absorbent cottom material such as cotton towelling. The clarification 'can be effected even when much larger proportions of water are employed, for example when the textile material is saturated with water, though the time taken to effect clarification at ordinary temperatures may be much longer than when a smaller proportion of water is used.

The requisite proportion of water can be applied as such, for example in the manner described above or by immersion followed by squeezing as in a padding mangle or by immersion followed by centrifuging.

Another method which has been found convenient for incorporating a limited proportion of water in the material is to apply the water as a mixture with a water-miscible liquid. The latter, if sufiiciently volatile, can then be substantially removed by evaporation leaving the water. Again if the water-miscible liquid is miscible with the hydrophobe liquid subsequently to be applied, the material wetted with the mixture may be introduced directly into the hydrophobe liquid. Suitable water-miscible liquids are acetone, methyl-ethyl ketone, methanol, ethanol, normal or iso-propyl alcohol, and diacetin. Thus a mixture of 100 volumes of one of these liquids with 8 to volumes of water can be used and the textile material immersed therein, drained, and immersed in the hydrophobe liquid while still wet.

In order to secure the best results it is desirable that the temperature at which the material is subjected to the combined action of water and the hydrophobe organic compound should not be unduly high. In general the temperature should be below 100 C. and preferably well below as already mentioned good results can- 100 C., for example below 85 0., though raising the temperature to a point somewhat above atmospheric temperature is often desirable in that the time necessary to secure clarification i thereby reduced. The optimum temperature varies with the hydrophobe liquid employed and the proportion of water present. ,For example when the material is saturated with water it is helpful to use a Volatile hydrophobe liquid, e. g. one having a boiling point below 150 0., heated to-such a temperature, which should not exceed 100 C., that water passes 01f with vapour of the liquid as an azeotropic mixture. For example perchlorethylene heated to about 80 C. may be used.

When a volatile hydrophobe liquid, whether hot or cold, is used for the treatment the clarified material may subsequently be freed from the said liquid by evaporation without the material losing its desirable properties in respect of uniformity of appearance on ubsequent oiling or like treatment. The valuable properties, however, may disappear if the material is left in a normal atmosphere for prolonged periods; to obtain the full benefit of the treatment therefore the oiling or like treatment should preferably be carried out within a few hours. Further, after drying off the hydrophobe liquid the material should not be wetted with water and allowed to dry prior to the oiling or like treatment. If desired, however, the material may be subjected to one or more further wetting treatments each being followed by treatment with a hydrophobe liquid as described above. This repetition of the treatment i sometimes of benefit as regards the clarity of the ultimate textile materials after oiling or the like.

The methods hereinbefore more particularly outlined contemplate the presence of the water in the textile material at the time the latter is brought into contact with the hydrophobe organic compound. This is not essential for it has been found that clarification can be eifected when the material is subjected to the action of a liquid composition containing both water and the hydrophobe organic compound, with or without a volatile common solvent, the clarification effect being more particularly evident when water and any volatile common solvent is subsequently removed by evaporation so as to leave the hydrophobe compound on the textile material. This can very readily be done when the hydrophobe organic liquid is substantially non-volatile. Preferably the water content of the mixture should be at least 10 or 15 per cent. A particularly useful application of this method is to impregnate the textile material with a film-forming composition comprising a hydrophobe organic liquid, the said composition containing water, preferably to the extent of at least 10 or 15 per cent. Thus the film-forming composition may be essentially hydrophobe in character [e. g. a drying oil, or drying oil varnish or a solution of a filmforming material (for example a cellulose ester or ether) in a volatile hydrophobe liquid] having water emulsified therein. Again it may contain a hydrophobe organic liquid, preferably one which i substantially non-volatile and compatible with the film-forming material, and water together in solution in a suitable volatile organic liquid, e. g. acetone. An example of such a composition is one containing cellulose acetate, di-(methoxyethyl) -phthalate or other di-ester of phthalic acid (or other substantially water-insoluble plasticiser for cellulose acetate), cyclohexanol, acetone and water. The water may constitute from 20 to 30 per cent of the acetone and water to gether. For instance by impregnating a light weight fabric of regenerated cellulose yarns (made by stretching cellulose acetate yarns in wet steam and saponifying substantially completely), with such a composition and evaporating off the acetone and water a clear product can be obtained whereas the omission of the water may result in a fabric marred by the presence of opaque yarns. Good results can also be obtained when using a composition substantially free from water if the evaporation of at least part of the acetone or other water miscible volatile liquid is carried out in a humid atmosphere, e. g. one of which the relative humidity is at least 50 per cent, at a temperature so low that blushing occurs due to deposition of water on the coating. Inclusion of water in the coating composition is however generally more convenient.

As mentioned above, if the clarified material is, before oiling or the like, wetted with water and dried, the oiled or similarly treated product is not of the high degree of clarity otherwise obtainable. This phenomenon can be utilised to produce oiled materials-exhibiting pattern eil'ects. Thus the textilemateria'lrafter clarification by water and hydrophobe liquid can be dried and water or a thickened aqueous preparation, e. g. an aqueous solution of methyl cellulose, gum arable, gum tragacanth or the like,- applied in a pattern, for example by printing, stencilling, etc. After drying the locally treated material is subjected to oiling or similar treatment whereupon patterned material is obtained, the portions which have been treated with water showing up due to their being less clear than the non-wetted portions.

Pattern effects can also be obtained by applying the clarifying treatment locally. For instance the water or mixture of water and a watermiscible organic liquid may be applied locally to the materials, for example by printing or stencilling or by immersion after the application of a hydrophobe resists; e. g. a wax, fat. or fatty acid. The locally wetted material is then subjected to the action of the hydrophobe liquid, as

described above, and upon oiling or the like exhibits pattern effects.

The new .treatment'is of especial value in the case of cellulose textiles whether of natural or regenerated cellulose. Thus it can be applied to cotton materials or to materials of cellulose regenerated from viscose or cuprammonium solutions of cellulose or obtained by sa-ponification of cellulose ester textiles. It has been found of particular value in the case of textiles. of filaments of high tenacity, e. g. above 2' grams per denier, made by stretching cellulose acetate or other cellulose ester filaments in a softened condition, for example under the influence of a hot aqueous medium, e. g. wet steam or hot water, and subsequently saponifying them substantially completely. The treatment can be applied for instance to fabrics consisting wholly or in part of such stretched and saponifie'd filaments and including fabrics suitable-for oiling or the like and of the kind described in-U. S. Patent No. 2,370,946. Again, the treatment can be applied'to textiles of filaments of high tenacity made by spinning viscose solutions or cuprammonium solutions of cellulose and stretching the filaments very substantially when partially but not completely set; The process can, however, be applied to textile materials of filaments other than cellulose filaments,- e. g. to materiai of natural silk or of cellulose acetate or other cellulose ester or ether filaments, including cellulose ester of ether filaments which have been stretched while in a softened condition, e. gt while under the influence of wet steam or hot water, and'cellulose ester or ether filaments produced by a wet spinning process.

The. invention is illustrated bythe following examples:

Example 1 A light weight fabric of regenerated cellulose yarns made by stretching cellulose acetate yarns to about 10 times their original length in wet steam and then saponifying substantially conipletely is passed in succession'throu'gh a series of zones containing alternately water and percl'll'orethylene. the latter heated to about 80 C. The first zone is'- of water and the final zone of perchlorethylene. After leaving: the final perchlorethylene zone the material is dried and immediately oiled bypassing through cold boiled linseed oil or a'linseed'oil varnish doctor blades being used toscrape off superfluous oil. The pro-*- portion of oil or varnish left On the material is suficient to close the pores substantially completely. The drying of the oil or varnish is effected in the well known manner, for example by means of air at to C. The resulting product is an oiled silk free from the o aque illarzients which. are in evidence when oiling is effected directlyand without the treatment with water and perchlorethylene. The treatment with water and perchlorethylene is conveniently effected in an apparatus comprising a tank containing perchlorethylene heated tothe desired temperature and having a substantial layer of water floating on the surface. Two series of horizontal guide rollers are provided, one series near the bottom of the tank and the other series in the upper part of the tank and above the level of the perchlorethylene. Those rollers serve to guide the fabric down through the water into the perchlorethylene thence up into the water and again down into the perehlorethylene and so on. Near the end of the tank at which the fabric leaves is a vertical baifie extending across the width of the tank and reaching down into the perchlorethylene. The small end'section of the tank so formed does not contain water so that the fabric can leave the tank directly after passing through perchlorethylene and without again passing through water. After leaving" this apparatus the fabric is dried and then passes on to an oiling apparatus. 7

The a paratus is illustrated-in the accompanying drawing and comprises a tank l provided with a vertical partition 2 which does not extend to the bottom of the tank but serves to divide the" tank into a section 3 and a smaller section l. The tank l contains a'series of horizontal guide rollers 5, 5, I, 8 near the bottom of the tank a second series of guide rollers 9, H], II, at ahigher' level. A pair of squeeze rollers l2, l't' is provided above the smaller section 4 of the tank l which is also provided with a cover Id. In use the apparatus contains perchl'orethylene up to the level shown at [5. Above the perchlorethylene insection 3 of the tank I is a layer of water extendiri'gjup to the'le'vel shown at [6. The perchlorethylene is heated (by means not shown); the fabric l'l' enters the tank I passing downwards through the water layer and then in succession under roller 5 and over roller 9 and soon, finally leaving the tank through the per chlorethylene in the smaller section 4 of the tank and through the squeeze rollers l2, l3, which serve to remove the bulk of the perchlorethylene which wouldfotherwise be carried away by the fabric.

Example 2 A fabric such as that referred to in Example 1 immersed. for about one minute in a mixture of 109 volumes of acetone with 10' to 15 volumes of water. drained, and immersed in cold benzene until the material appears clear and free from milky patches which may require some hours. It is then dried and immediately oiled in" the manner described in Example 1. If desired, though with rather less satsifactory results, the benzene treatment may be omitted and the ma.- terial placed directly in the cold oil and left until clear; it is then freed from superfluous oil and dried for several hours in air at 75 to 95" C.

Example 3' A fabric such that referred to in Example 1 is doped with the following composition the parts referred to being parts by weight:

Parts Cellulose acetate 7.5 Acetone (95 155 Di- (methoxyethyl) -phthalate 21.5 Cyclohexanol 15.5 Water 50 A fabric such as that referred to in Example 1 is treated with a mixture of acetone and water and then with benzene as described in Example 2. It is then dried and printed in a pattern with water thickened with about 1 per cent of watersoluble methyl cellulose. The material is again dried and then oiled with cold boiled linseed oil as described in Example 1. The resulting fabric is clear except in the printed portions, these exhibiting opaque threads.

Having described our invention, what we desire to secure by Letters Patent is:

1. Process for impregnating fabric with a hydrophobe film-forming material so that the fabric has a substantially uniform degree of transparency, said fabric being of regenerated cellulose filaments made by stretching cellulose ester filamerits in a softened condition and saponifying them substantially completely, which comprises wetting the fabric with water and subjecting it while moist with at least 22% of its own weight of water to the action of a hydrophobe organic liquid immiscible with water selected from the group consisting of benzene, toluene, xylene, solvent naphtha, light fractions of petroleum, carbon tetrachloride, perchloroethylene and methyl cyclohexanol until the fabric has a substantially uniform appearance therein, and thereafter impregnating the fabric with a hydrophobe liquid capable of yielding a transparent film on drying, and causing the latter liquid to dry.

2. Process according to claim 1 wherein the water-moist fabric carries at least 50% of its weight of water based on the dry weight of the fabric.

3. Process for impregnating fabric with a hydrophobe film-forming material so that the fabric has a substantially uniform degree of transparency, said fabric being of regenerated cellulose filaments made by stretching cellulose acetate filaments in a softened condition and saponifying them substantially completely, which comprises wetting the fabric with water and subjecting it which moist with at least 22% of its own weight of water to the action of a hydrophobe organic liquid immiscible with water selected from the group consisting of benzene, toluene, xylene, solvent naphtha, light fractions of petroleum, carbon tetrachloride, perchloroethylene and methyl cyclohexanol until the fabric has a substantially uniform appearance therein, and thereafter impregnating the fabric with a hydrophobe liquid capable of yielding a transparent film on drying, and causing the latter liquid to dry.

4. Process for impregnating fabric with a hydrophobe film-forming material so that the 8 fabric has a substantially uniform degree of transparency, said fabric being of regenerated cellulose filaments made by stretching cellulose acetate filaments in a softened condition and saponifying them substantially completely, which comprises wetting the fabric with water and subjecting it while moist with at least 22% of its own weight of water to the action of cold benzene until the fabric has a substantially uniform appearance therein, and thereafter impregnating the fabric with a hydrophobe liquid capable of yielding a transparent film on drying, and causing the latter liquid to dry.

5. Process for impregnating fabric with a hydrophobe film-forming material so that the fabric has a substantially uniform degree of transparency, said fabric being of regenerated cellulose filaments made by stretching cellulose acetate filaments in a softened condition and saponifying them substantially completely, which comprises wetting the fabric with water and subjecting it while moist with at least 22% of its own weight of water to the action of perchlorethylene at a temperature of about C. until the fabric has a substantially uniform appearance therein, and thereafter impregnating the fabric with a hydrophobe liquid capable of yielding a transparent film on drying, and causing the latter liquid to dry.

6. Process for impregnating fabric with a hydrophobe drying oil composition so that the fabric has a substantially uniform degree of transparency, said fabric being of regenerated cellulose filaments made by stretching cellulose acetate filaments in a softened condition and saponifying them substantially completely, which comprises wetting the fabric with water and subjecting it while moist with at least 22% of its own weight of water to the action of a hydrophobe organic liquid immiscible with water selected from the group consisting of benzene, toluene, xylene, solvent naphtha, light fractions of petroleum, carbon tetrachloride, perchloroethylene and methyl cyclohexanol until the fabric has a substantially uniform appearance therein and thereafter impregnating the fabric with a liquid hydrophobe drying oil composition and causing the latter to dry.

'7. Process for impregnating fabric with a hydrophobe drying oil composition so that the fabric has a substantially uniform degree of transparency, said fabric being of regenerated cellulose filaments made by stretching cellulose acetate filaments in a softened condition and saponifying them substantially completely, which comprises wetting the fabric with water and subjecting it while moist with at least 22% of its own weight of water to the action of cold benzene until the fabric has a substantially uniform appearance therein, and thereafter impregnating the fabric with a liquid hydrophobe drying oil composition and causing the latter to dry.

8. Process for impregnating fabric with a hydrophobe drying oil composition so that the fabric has a substantially uniform degree of transparency, said fabric being of regenerated cellulose filaments made by stretching cellulose acetate filaments in a softened condition and saponifying them substantially completely, which comprises wetting the fabric with water and subjecting it while moist with at least 22% of its own weight of water to the action of perchlorethylene at a temperature of about 80 C. until the fabric has a substantially uniform appearance therein, and thereafter impregnating 9 the fabric with a sumcient quantity of a liquid hydrophobe drying oil composition to close the pores in the fabric and causing the latter to dry.

ALBERT MELLOR. RALPH JAMES MANN. DONALD FINLAYSON. ALBERT WILLIAM MORLEDGE-HADFIEID.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 138,302 Wagner Apr. 29, 1873 217,604 Francis July 15, 1879 1,236,959 McIntosh Aug. 14, 1917 Number 10 Number OTHER REFERENCES Eliminating Bubbles in Fabric Impregnation, Randolph, Chem. and Met. Eng. vol. 35, Nov. 5, 

